Water-soluble metalworking fluid

ABSTRACT

Provided is a water-soluble metalworking oil comprising a base oil (A) comprising oil-soluble polyalkylene glycol (A1), wherein a total content of water-soluble polyalkylene glycol and methoxypolyethylene glycol is less than 60% by mass based on the total amount excluding water.

TECHNICAL FIELD

The present invention relates to a water-soluble metalworking oil, ametalworking fluid obtained by blending the water-soluble metalworkingoil with dilution water, and a metalworking method comprising processinga workpiece comprising metal by application of the metalworking fluid.

BACKGROUND ART

In the art of metalworking such as cutting and grinding, metalworkingfluids are used to increase workability for workpieces and to suppresswear of working tools.

Metalworking fluids include oil-based metalworking fluids containingoils such as mineral oils, synthetic oils, and animal and vegetable oilsas main components, and water-soluble metalworking fluids provided withwater solubility by blending an oil with a surface-active compound.Recently, water-soluble metalworking fluids are increasingly used forsafety reasons such as a reduced risk of catching fire.

For example, Patent Literature 1 discloses an invention which relates toa concentrated metalworking fluid comprising from 60 to 90 percent byweight of base oil selected from the group consisting of water-solublepolyalkylene glycols, methoxypolyethylene glycols, and combinations oftwo or more thereof; from 5 to 20 percent by weight of glycol ether;0.01 to 5 percent by weight of oil-soluble polyalkylene glycol; and from0.2 to 6 percent by weight of additives.

Moreover, Patent Literature 2 discloses an invention which relates to awater-soluble working oil comprising methyldicyclohexylamine.

CITATION LIST Patent Literature

-   Patent Literature 1-   International Publication No. WO 2014/089766-   Patent Literature 2-   International Publication No. WO 2010/113594

SUMMARY OF INVENTION Technical Problem

Under such circumstances, the demand exists for novel water-solublemetalworking oils, e.g., also as emulsion-type and soluble-type oils,that have various improved characteristics so as to be more readilyapplicable to metalworking than conventional metalworking oils.

Solution to Problem

The present invention provides a water-soluble metalworking oilcontaining oil-soluble polyalkylene glycol as a base oil and having acontent of water-soluble polyalkylene glycol and methoxypolyethyleneglycol that is equal to or less than a predetermined amount.Specifically, the present invention provides, for example, the followingembodiments [1] to [16]:

[1] A water-soluble metalworking oil comprising a base oil (A)comprising oil-soluble polyalkylene glycol (A1), wherein a total contentof water-soluble polyalkylene glycol and methoxypolyethylene glycol isless than 60% by mass based on the total amount excluding water.[2] The water-soluble metalworking oil according to [1], wherein thetotal content of water-soluble polyalkylene glycol andmethoxypolyethylene glycol is less than 10 parts by mass based on 100parts by mass of the total amount of component (A1).[3] The water-soluble metalworking oil according to [1] or [2], which issubstantially free of a sulfuric extreme pressure agent.[4] The water-soluble metalworking oil according to any one of [1] to[3], further comprising water (B).[5] The water-soluble metalworking oil according to any one of [1] to[4], wherein the content of component (A1) in component (A) is 10 to100% by mass based on the total amount of component (A) contained in thewater-soluble metalworking oil.[6] The water-soluble metalworking oil according to any one of [1] to[5], wherein the content of component (A1) is 0.01% by mass or morebased on the total amount of the water-soluble metalworking oilexcluding water.[7] The water-soluble metalworking oil according to any one of [1] to[6], further comprising an amine compound (C).[8] The water-soluble metalworking oil according to any one of [1] to[7], further comprising a fatty acid (D).[9] The water-soluble metalworking oil according to any one of [1] to[8], further comprising a nonionic surfactant (E).[10] The water-soluble metalworking oil according to any one of [1] to[9], which is an emulsion-type oil classified as A1 as stipulated in JISK 2241:2017.[11] The water-soluble metalworking oil according to any one of [1] to[9], which is a soluble-type oil classified as A2 as stipulated in JIS K2241:2017.[12] A water-soluble metalworking oil comprising a base oil (A)comprising oil-soluble polyalkylene glycol (A1), wherein a total contentof water-soluble polyalkylene glycol and methoxypolyethylene glycol isless than 10 parts by mass based on 100 parts by mass of the totalamount of component (A).[13] A metalworking fluid obtained by blending the water-solublemetalworking oil of any one of [1] to [12] with dilution water.[14] A metalworking method comprising processing a workpiece comprisingmetal by application of the metalworking fluid according to [13].[15] The metalworking method according to [14], wherein the workpiecehas a member comprising at least iron or aluminum.[16] The metalworking method according to [14] or [15], whereincorrosion of a copper-containing member constituting a processingmachine used in processing of the workpiece is suppressed.

Advantageous Effects of Invention

The water-soluble metalworking oil of one preferable embodiment of thepresent invention can be prepared into a metalworking fluid having avariety of excellent characteristics such as workability by beingdiluted with dilution water.

DESCRIPTION OF EMBODIMENT

Concerning the numerical ranges described herein, the upper limits andthe lower limits can be suitably combined. For example, when a numericalrange is described as being “preferably 30 to 100, and more preferably40 to 80”, the range of “30 to 80” and the range of “40 to 100” are alsoincluded in the numerical range described herein. Moreover, for example,when a numerical range is described as being “preferably 30 or more andmore preferably 40 or more, and preferably 100 or less and morepreferably 80 or less”, the range of “30 to 80” and the range of “40 to100” are also included in the numerical range described herein.

In addition, for example, “60 to 100” as a numerical range describedherein means the range of “60 or more and 100 or less”.

Herein, the “metalworking oil” is a stock solution of a metalworkingfluid before being diluted with dilution water to provide a metalworkingfluid, and is in a form suitable for transportation and storage beforebeing used in metalworking. The “metalworking fluid” is what is obtainedby adding dilution water to a stock solution of a metalworking oil todilute the stock solution, and is in a form suitable when used inmetalworking.

The “metalworking oil” and the “metalworking fluid” can be distinguishedaccording to, for example, the water content as follows:

-   -   “Metalworking oil”: the water content is 0 parts by mass or more        and 400 parts by mass or less based on 100 parts by mass of the        total amount of components other than water; and    -   “Metalworking fluid”: the water content is more than 400 parts        by mass based on 100 parts by mass of the total amount of        components other than water.

[Configuration of Water-Soluble Metalworking Oil]

The water-soluble metalworking oil of the present invention is an oilthat contains a base oil (A) containing oil-soluble polyalkylene glycol(hereinafter also referred to as “oil-soluble PAG”) (A1), and that isregulated such that the total content of water-soluble polyalkyleneglycol (hereinafter also referred to as “water-soluble PAG”) andmethoxypolyethylene glycol (hereinafter also referred to as “MPEG”) is apredetermined content.

Herein, the term “water-soluble” means a component that the amount ofthe component soluble in 100 g of water at 25° C. is 20 g or more, andthe total light transmittance of a solution at 25° C. prepared by adding20 g of the component to 100 g of water at 25° C. is 90% or more.

In the following description of the present specification, the componentdescribed as being “water-soluble” is a component having the abovecharacteristics.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the total content of water-soluble PAG and MPEG may be lessthan 60% by mass, less than 50% by mass, less than 40% by mass, lessthan 30% by mass, less than 20% by mass, less than 10% by mass, lessthan 5% by mass, less than 1% by mass, or less than 0.1% by mass basedon the total amount (100% by mass) excluding water.

Moreover, in the water-soluble metalworking oil of one embodiment of thepresent invention, the total content of water-soluble PAG and MPEG maybe less than 10 parts by mass, less than 5 parts by mass, less than 1part by mass, less than 0.1 parts by mass, less than 0.01 parts by mass,or less than 0.001 parts by mass based on 100 parts by mass of the totalamount of component (A1).

The above water-soluble metalworking oil of one embodiment of thepresent invention may further contain water (B). By regulating thecontent of water (B), the water-soluble metalworking oil can be preparedinto an emulsion-type oil classified as A1 or a soluble-type oilclassified as A2 as stipulated in JIS K 2241:2017.

Moreover, the above water-soluble metalworking oil of one embodiment ofthe present invention preferably contains one or more selected from anamine compound (C), a fatty acid (D), and a nonionic surfactant (E),more preferably contains at least components (C) and (D), and even morepreferably contains all components (C), (D), and (E).

The water-soluble metalworking oil of one embodiment of the presentinvention may contain a further component other than the components (A)to (E) as long as the effects of the present invention are not impaired.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the total content of the components (A) and (B) is preferably20% by mass or more, more preferably 30% by mass or more, even morepreferably 40% by mass or more, yet more preferably 45% by mass or more,and particularly preferably 50% by mass or more, and may be 100% by massor less, 95% by mass or less, 90% by mass or less, 85% by mass or less,80% by mass or less, 75% by mass or less, 70% by mass or less, 65% bymass or less, or 60% by mass or less based on the total amount (100° bymass) of the water-soluble metalworking oil.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the total content of the components (A) to (D) is preferably30% by mass or more, more preferably 40% by mass or more, morepreferably 50% by mass or more, even more preferably 60% by mass ormore, yet more preferably 70% by mass or more, and particularlypreferably 80% by mass or more, and may be 100% by mass or less, 98% bymass or less, 95% by mass or less, 93% by mass or less, or 90% by massor less based on the total amount (100% by mass) of the water-solublemetalworking oil.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the total content of the components (A) to (E) is preferably35% by mass or more, more preferably 45% by mass or more, even morepreferably 55% by mass or more, yet more preferably 65% by mass or more,further preferably 75% by mass or more, and particularly preferably 85%by mass or more, and may be 100% by mass or less, 98% by mass or less,96% by mass or less, or 94% by mass or less based on the total amount(100% by mass) of the water-soluble metalworking oil.

Below, the respective components contained in the water-solublemetalworking oil of one embodiment of the present invention will now bedescribed.

<Component (A): Base Oil>

The water-soluble metalworking oil of the present invention contains abase oil (A) containing oil-soluble PAG (A1).

Containing oil-soluble PAG as a base oil, the water-soluble metalworkingoil of the present invention is capable of enhancing the workability ofa metalworking fluid obtained by blending the water-soluble metalworkingoil with dilution water.

Generally, to form a metalworking fluid having excellent workability(especially workability for an iron-containing workpiece), thewater-soluble metalworking oil, which is a stock solution thereof,contains a sulfuric extreme pressure agent. However, the sulfuricextreme pressure agent causes corrosion of a copper-containing memberthat constitutes a processing machine used during metalworking of aworkpiece. On the other hand, by containing component (A1), thewater-soluble metalworking oil of the present invention can be preparedinto a metalworking fluid having excellent workability while beingsubstantially free of a sulfuric extreme pressure agent and, also, canavoid the problem of corroding the copper-containing member.

Component (A) used in one embodiment of the present invention maycontain another base oil (A2) other than component (A1).

However, in the water-soluble metalworking oil of one embodiment of thepresent invention, the content of component (A1) in component (A), fromthe viewpoint of providing a water-soluble metalworking oil capable ofbecoming a metalworking fluid having excellent workability, may be 10 to100% by mass, 20 to 100% by mass, 30 to 100% by mass, 40 to 100% bymass, 50 to 100% by mass, 60 to 100% by mass, 70 to 100% by mass, 75 to100% by mass, 80 to 100% by mass, 85 to 100% by mass, 90 to 100% bymass, 95 to 100% by mass, or 98 to 100% by mass based on the totalamount (100% by mass) of component (A) contained in the water-solublemetalworking oil.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the content of component (A), from the viewpoint of providinga water-soluble metalworking oil capable of becoming a metalworkingfluid having excellent workability, may be preferably 0.01% by mass ormore, more preferably 0.05% by mass or more, more preferably 0.1% bymass or more, more preferably 0.5% by mass or more, more preferably 1.0%by mass or more, even more preferably 1.5% by mass or more, even morepreferably 2.0% by mass or more, even more preferably 2.5% by mass ormore, even more preferably 3.0% by mass or more, yet more preferably4.0% by mass or more, yet more preferably 5.0% by mass or more, yet morepreferably 6.0° by mass or more, yet more preferably 7.0% by mass ormore, yet more preferably 8.0% by mass or more, particularly preferably9.0% by mass or more, moreover, 9.5% by mass or more, 10.0% by mass ormore, 11.0% by mass or more, or 12.0% by mass or more, and may be 100%by mass or less, 99% by mass or less, 95% by mass or less, 90% by massor less, 85% by mass or less, 80% by mass or less, 75% by mass or less,or 70% by mass or less based on the total amount (100% by mass) of thewater-soluble metalworking oil excluding water.

When providing an emulsion-type oil classified as A1 as stipulated inJIS K 2241:2017, the content of component (A) may be 10° by mass ormore, 15° by mass or more, 20% by mass or more, 30% by mass or more, 40%by mass or more, 45% by mass or more, or 50% by mass or more based onthe total amount (100% by mass) of the oil excluding water, and theupper limit is as described above.

When providing a soluble-type oil classified as A2 as stipulated in JISK 2241:2017, the content of component (A) may be 60% by mass or less,50% by mass or less, 40% by mass or less, 30% by mass or less, 25% bymass or less, or 20% by mass or less based on the total amount (100% bymass) of the oil excluding water, and the lower limit is as describedabove.

Moreover, in the water-soluble metalworking oil of one embodiment of thepresent invention, the content of component (A), from the viewpoint ofproviding a water-soluble metalworking oil capable of becoming ametalworking fluid having excellent workability, may be preferably 0.01%by mass or more, more preferably 0.05% by mass or more, more preferably0.1% by mass or more, more preferably 0.3% by mass or more, morepreferably 0.5% by mass or more, even more preferably 0.7% by mass ormore, even more preferably 1.0% by mass or more, even more preferably1.5% by mass or more, even more preferably 2.0% by mass or more, yetmore preferably 2.5% by mass or more, yet more preferably 3.0% by massor more, yet more preferably 3.5° by mass or more, particularlypreferably 4.0% by mass or more, moreover, 4.5% by mass or more, 5.0% bymass or more, 5.5% by mass or more, 6.0% by mass or more, 6.5% by massor more, or 7.0% by mass or more, and is 100% by mass or less, but inconsideration of the content of other components, may be 99% by mass orless, 95% by mass or less, 90% by mass or less, 85% by mass or less, 80%by mass or less, 75% by mass or less, 70% by mass or less, 65% by massor less, or 60% by mass or less based on the total amount (100% by mass)of the water-soluble metalworking oil.

When forming an emulsion-type oil classified as A1 as stipulated in JISK 2241:2017, the content of component (A) may be 10% by mass or more,15% by mass or more, 20° by mass or more, 30° by mass or more, 40° bymass or more, 45% by mass or more, or 50% by mass or more based on thetotal amount (100% by mass) of the oil, and the upper limit is asdescribed above.

When forming a soluble-type oil classified as A1 as stipulated in JIS K2241:2017, the content of component (A) may be 60% by mass or less, 50%by mass or less, 40% by mass or less, 30% by mass or less, 25% by massor less, 20% by mass or less, 15% by mass or less, or 10% by mass orless based on the total amount (100% by mass) of the oil, and the lowerlimit is as described above.

<<Component (A1): Oil-Soluble Polyalkylene Glycol (Oil-Soluble PAG)>>

Component (A1) used in one embodiment of the present invention is notparticularly limited as long as it has a structural unit derived fromalkylene oxide and is polyalkylene glycol (PAG) that demonstrates oilsolubility.

Herein, whether the PAG of interest is oil-soluble or not is determinedby its miscibility with a mineral oil that is classified into Group 1 ofthe API (American Petroleum Institute) base oil category. Specifically,the PAG of interest is determined as oil-soluble PAG when a samplehaving a mass ratio of the content of the PAG of interest to the contentof a mineral oil classified into Group 1 [PAG/mineral oil] of 10/90 or90/10 is prepared, then the total light transmittances at 25° C. of thesample and a standard are measured, and the following criteria (i) and(ii) are satisfied:

-   -   (i) When a sample has a content ratio [PAG/mineral oil]=10/90,        [Total light transmittance of the sample (%)]−[Total light        transmittance of mineral oil only (%)]≤20%; and    -   (ii) When a sample has a content ratio [PAG/mineral oil]=90/10,        [Total light transmittance of the sample (%)]−[Total light        transmittance of PAG (%)]≤20%.

In the following description of the present specification, the componentdescribed as being “oil-soluble” is a component that satisfies the abovecriteria (i) and (ii) unless specified otherwise.

Examples of component (A1) used in one embodiment of the presentinvention include polymers having a structural unit derived from atleast one of propylene oxide and butylene oxide, such as a propyleneoxide homopolymer, a butylene oxide homopolymer, and a propyleneoxide/butylene oxide copolymer.

One component (A1) may be used singly, or two or more may be used incombination.

From the viewpoint of providing a water-soluble metalworking oil capableof becoming a metalworking fluid having excellent workability, thekinematic viscosity at 40° C. of component (A1) used in one embodimentof the present invention is preferably 9 to 800 mm²/s, more preferably15 to 350 mm²/s, more preferably 20 to 250 mm²/s, even more preferably23 to 180 mm²/s, yet more preferably 25 to 100 mm²/s, yet morepreferably 28.8 to 90 mm²/s, and particularly preferably 40 to 80 mm²/s.

From the viewpoint of providing a water-soluble metalworking oil capableof becoming a metalworking fluid having excellent workability, theviscosity grade as stipulated in ISO 3448 of component (A1) used in oneembodiment of the present invention is preferably VG10, VG15, VG22,VG32, VG46, VG68, VG100, VG150, VG220, VG320, VG460, or VG680, morepreferably VG22, VG32, VG46, VG68, or VG100, even more preferably VG32,VG46, or VG68, yet more preferably VG46 or VG68, and particularlypreferably VG68.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the content of component (A1), from the viewpoint ofproviding a water-soluble metalworking oil capable of becoming ametalworking fluid having excellent workability, may be preferably 0.01%by mass or more, more preferably 0.05% by mass or more, more preferably0.1° by mass or more, more preferably 0.5% by mass or more, morepreferably 1.0% by mass or more, even more preferably 1.5% by mass ormore, even more preferably 2.0% by mass or more, even more preferably2.5% by mass or more, even more preferably 3.0% by mass or more, yetmore preferably 4.0% by mass or more, yet more preferably 5.0% by massor more, yet more preferably 6.0% by mass or more, yet more preferably7.0% by mass or more, yet more preferably 8.0% by mass or more,particularly preferably 9.0% by mass or more, moreover, 9.5% by mass ormore, 10.0% by mass or more, 11.0% by mass or more, or 12.0% by mass ormore, and is 100% by mass or less, but in consideration of the contentof other components, may be 95° by mass or less, 90% by mass or less,85% by mass or less, 80% by mass or less, 75% by mass or less, 70% bymass or less, or 65% by mass or less based on the total amount (100% bymass) of the water-soluble metalworking oil excluding water.

When providing an emulsion-type oil classified as A1 as stipulated inJIS K 2241:2017, the content of component (A1) may be 10% by mass ormore, 15% by mass or more, 20% by mass or more, 30% by mass or more, 40%by mass or more, 45% by mass or more, or 50% by mass or more based onthe total amount (100% by mass) of the oil excluding water, and theupper limit is as described above.

When providing a soluble-type oil classified as A2 as stipulated in JISK 2241:2017, the content of component (A1) may be 60% by mass or less,50% by mass or less, 40% by mass or less, 30% by mass or less, 25% bymass or less, or 20% by mass or less based on the total amount (100% bymass) of the oil excluding water, and the lower limit is as describedabove.

<<Component (A2): Base Oil Other than Component (A1)>>

The base oil (A2) other than component (A1) used in one embodiment ofthe present invention may be at least one selected from mineral oils andsynthetic oils other than oil-soluble PAG.

Herein, the above water-soluble polyalkylene glycol (water-soluble PAG)and methoxypolyethylene glycol (MPEG) are also included in component(A2), and the total content of water-soluble PAG and MPEG is regulatedas described above.

Examples of mineral oils include atmospheric residue obtained byperforming atmospheric distillation on crude oil such as paraffiniccrude oil, intermediate crude oil, and naphthenic crude oil; distillateobtained by performing vacuum distillation on such atmospheric residue;and refined oil obtained by performing on such distillate one or morerefining treatments such as solvent deasphalting, solvent extraction,hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining.

Examples of synthetic oils include polyα-olefins such as α-olefinhomopolymers or α-olefin copolymers (e.g., α-olefin copolymers having 8to 14 carbon atoms, such as ethylene-α-olefin copolymers); isoparaffin;ester oils such as polyol esters, dibasic acid esters, and phosphoricacid esters; ether oils such as polyphenyl ether; alkylbenzene; alkylnaphthalene; synthetic oils (GTL) obtained by isomerizing wax (GTL wax(Gas-To-Liquids WAX)) produced from natural gas by Fischer-Tropschprocess or the like.

From the viewpoint of providing a water-soluble metalworking oil capableof becoming a metalworking fluid having excellent workability, thekinematic viscosity at 40° C. of component (A2) used in one embodimentof the present invention is preferably 2.0 to 150 mm²/s, more preferably3.0 to 120 mm²/s, even more preferably 5.0 to 100 mm²/s, yet morepreferably 6.0 to 90 mm²/s, and particularly preferably 7.0 to 80 mm²/s.

The viscosity index of component (A2) used in one embodiment of thepresent invention is preferably 70 or more, more preferably 80 or more,even more preferably 90 or more, yet more preferably 100 or more, andparticularly preferably 105 or more.

<Component (B): Water>

The water-soluble metalworking oil of one embodiment of the presentinvention may further contain water (B). Containing water, thewater-soluble metalworking oil becomes flame retardant and thus has goodhandleability as a non-hazardous material during storage.

Water, which is component (B) used in one embodiment of the presentinvention, is not particularly limited, and may be, for example,distilled water, ion exchanged water, tap water, or water for industrialuse.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the content of component (B) is 400 parts by mass or less,preferably 1 to 350 parts by mass, more preferably 2 to 300 parts bymass, more preferably 3 to 250 parts by mass, and even more preferably 5to 200 parts by mass based on 100 parts by mass of the total amount ofcomponents other than water of the water-soluble metalworking oil.

When providing an emulsion-type oil classified as A1 as stipulated inJIS K 2241:2017, the content of component (B) may be 150 parts by massor less, 100 parts by mass or less, 70 parts by mass or less, 50 partsby mass or less, 40 parts by mass or less, 30 parts by mass or less, 20parts by mass or less, or 15 parts by mass or less based on 100 parts bymass of the total amount of components excluding water in thewater-soluble metalworking oil, and the lower limit is as describedabove.

When providing a soluble-type oil classified as A2 as stipulated in JISK 2241:2017, the content of component (B) may be 10 parts by mass ormore, 30 parts by mass or more, 50 parts by mass or more, 60 parts bymass or more, 70 parts by mass or more, 80 parts by mass or more, 90parts by mass or more, or 100 parts by mass or more based on 100 partsby mass of the total amount of components excluding water in thewater-soluble metalworking oil, and the upper limit is as describedabove.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the content of component (B) is preferably 1 to 99° by mass,more preferably 2 to 90% by mass, even more preferably 3 to 85% by mass,and yet more preferably 5 to 80% by mass based on the total amount (100%by mass) of the water-soluble metalworking oil.

When providing an emulsion-type oil classified as A1 as stipulated inJIS K 2241:2017, the content of component (B) may be 70% by mass orless, 60% by mass or less, 50% by mass or less, 40% by mass or less, 30%by mass or less, 25% by mass or less, 20% by mass or less, or 15% bymass or less based on the total amount (100% by mass) of thewater-soluble metalworking oil, and the lower limit is as describedabove.

When providing a soluble-type oil classified as A2 as stipulated in JISK 2241:2017, the content of component (B) may be 10° by mass or more,15° by mass or more, 20% by mass or more, 25% by mass or more, 30° bymass or more, 35% by mass or more, 40% by mass or more, 45% by mass ormore, or 50% by mass or more based on the total amount (100% by mass) ofthe water-soluble metalworking oil, and the upper limit is as describedabove.

<Component (C): Amine Compound>

Preferably, the water-soluble metalworking oil of one embodiment of thepresent invention further contains an amine compound (C). When thewater-soluble metalworking oil containing component (C) is combined withdilution water to be formed into a metalworking fluid, the metalworkingfluid can have a good emulsion state and more increased antibacterialproperties, antirust properties, workability, and the like.

One component (C) may be used singly, or two or more may be used incombination.

From the same viewpoint as above, in the water-soluble metalworking oilof one embodiment of the present invention, the content of component (C)may be preferably 3 to 70% by mass, more preferably 5 to 60% by mass,even more preferably 7 to 50% by mass, yet more preferably 10 to 45% bymass, particularly preferably 12 to 40% by mass, moreover, 15% by massor more, 17% by mass or more, 20% by mass or more, 22% by mass or more,or 24% by mass or more, and may be 37° by mass or less, 35° by mass orless, 33% by mass or less, 31% by mass or less, 27% by mass or less, or25% by mass or less based on the total amount (100% by mass) of thewater-soluble metalworking oil.

From the same viewpoint as above, in the water-soluble metalworking oilof one embodiment of the present invention, the content of component (C)may be preferably 2 to 40% by mass, more preferably 4 to 35% by mass,even more preferably 6 to 30% by mass, yet more preferably 8 to 25% bymass, particularly preferably 10 to 20% by mass, moreover, 11% by massor more, or 12% by mass or more, and may be 18° by mass or less or 16°by mass or less based on the total amount (100% by mass) of thewater-soluble metalworking oil.

Moreover, in the water-soluble metalworking oil of one embodiment of thepresent invention, the mass ratio of the content of component (C) to thecontent of component (A1) [(C)/(A1)] may be preferably 0.01 to 30, morepreferably 0.05 to 25, even more preferably 0.10 to 20, yet morepreferably 0.20 to 15, particularly preferably 0.25 to 9.0, moreover,0.28 or more, 0.30 or more, 0.40 or more, 0.50 or more, 0.60 or more,0.70 or more, 0.80 or more, 0.90 or more, 1.00 or more, 1.20 or more,1.40 or more, or 1.60 or more, and may be 8.0 or less, 7.0 or less, 6.0or less, 5.0 or less, 4.5 or less, 4.0 or less, 3.5 or less, 3.0 orless, 2.9 or less, 2.8 or less, 2.7 or less, 2.6 or less, 2.5 or less,or 2.4 or less.

Component (C) used in one embodiment of the present invention may be anyof monoamine having one amino nitrogen atom within one molecule, diaminehaving two amino nitrogen atoms within one molecule, and polyaminehaving 3 or more amino nitrogen atoms within one molecule.

However, from the viewpoint of providing a water-soluble metalworkingoil capable of becoming a metalworking fluid having more increasedantibacterial properties, antirust properties, workability, and thelike, component (C) used in one embodiment of the present inventionpreferably contains monoamine.

The content of monoamine is preferably 50 to 100% by mass, morepreferably 60 to 100% by mass, more preferably 70 to 100% by mass, morepreferably 75 to 100% by mass, even more preferably 80 to 100% by mass,even more preferably 85 to 100% by mass, yet more preferably 90 to 100%by mass, yet more preferably 95 to 100% by mass, and particularlypreferably 98 to 100% by mass based on the total amount (100% by mass)of component (C) contained in the water-soluble metalworking oil.

Monoamine used as component (C) in one embodiment of the presentinvention is classified according to the number of substituents R intoprimary monoamine represented by the following formula (i), secondarymonoamine represented by the following formula (ii), and tertiarymonoamine represented by the following formula (iii).

From the viewpoint of providing a water-soluble metalworking oil capableof becoming a metalworking fluid having a good emulsion state and moreincreased antibacterial properties, antirust properties, workability,and the like when combined with dilution water, component (C) used inone embodiment of the present invention preferably contains at leasttertiary monoamine, more preferably contains tertiary monoamine and atleast one of primary monoamine and secondary monoamine, and even morepreferably contains at least secondary monoamine and tertiary monoamine.

In the above formulae, R each independently represents a substituent. Aplurality of R may be the same or may be different from each other.Examples of the substituent include an alkyl group, a hydroxyalkylgroup, an alkenyl group, a cycloalkyl group, a phenyl group, and abenzyl group.

Examples of the alkyl group that can be selected as a substituent Rinclude a methyl group, an ethyl group, a propyl group (a n-propylgroup, an i-propyl group), a butyl group (a n-butyl group, an i-butylgroup, a s-butyl group, a t-butyl group), a pentyl group (a n-pentylgroup, an i-pentyl group, a neopentyl group), a hexyl group, a heptylgroup, an octyl group, a 2-ethylhexyl group, a nonyl group, a decylgroup, a undecyl group, a dodecyl group, a tridecyl group, a tetradecylgroup, a pentadecyl group, a hexadecyl group, a heptadecyl group, and anoctadecyl group.

The alkyl group may be a linear alkyl group or may be a branched alkylgroup.

The number of carbon atoms of the alkyl group is preferably 1 to 30,more preferably 1 to 20, even more preferably 1 to 10, yet morepreferably 1 to 6, and particularly preferably 1 to 4.

Examples of the hydroxyalkyl group that can be selected as a substituentR include groups obtained by replacing at least one hydrogen atom of theabove alkyl groups with a hydroxyl group.

The alkyl group that constitutes the hydroxyalkyl group may also be alinear alkyl group or may be a branched alkyl group.

The number of carbon atoms of the hydroxyalkyl group is preferably 1 to30, more preferably 1 to 20, even more preferably 1 to 10, yet morepreferably 1 to 6, and particularly preferably 2 to 4.

Examples of the alkenyl group that can be selected as a substituent Rinclude an ethenyl group (a vinyl group), a propenyl group, a butenylgroup, a pentenyl group, a hexenyl group, a heptenyl group, an octenylgroup, a nonenyl group, a decenyl group, a dodecenyl group, a tridecenylgroup, a tetradecenyl group, a pentadecenyl group, a hexadecenyl group,and an octadecenyl group.

The alkenyl group may be a linear alkenyl group or may be a branchedalkenyl group.

The number of carbon atoms of the alkenyl group is preferably 1 to 30,more preferably 1 to 20 carbon atoms, even more preferably 1 to 10carbon atoms, yet more preferably 1 to 6 carbon atoms, and particularlypreferably 1 to 3 carbon atoms.

Examples of the cycloalkyl group that can be selected as a substituent Rinclude a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, acyclohexyl group, a cycloheptyl group, a cyclooctyl group, and anadamantyl group.

From the viewpoint of providing a water-soluble metalworking oil capableof becoming a metalworking fluid having a good emulsion state and moreincreased antibacterial properties, antirust properties, workability,and the like, when combined with dilution water, component (C) used inone embodiment of the present invention preferably contains alkanolaminehaving at least one hydroxyalkyl group.

Examples of alkanolamine include primary alkanolamine in which R in theabove formula (i) is a hydroxyalkyl group, secondary alkanolamine inwhich at least one R in the above formula (ii) is a hydroxyalkyl group,and tertiary alkanolamine in which at least one R in the above formula(iii) is a hydroxyalkyl group.

Examples of primary alkanolamine include ethanolamine, propanolamine,butanolamine, and 2-amino-2-methyl-1-propanol.

Examples of secondary alkanolamine include monoethanolamine such asN-methylethanolamine, N-ethylethanolamine, N-propylethanolamine,N-butylethanolamine, N-octylethanolamine, N-stearylethanolamine,N-oleylethanolamine, N-cyclohexylethanolamine, N-phenylethanolamine, andN-benzylethanolamine; monopropanolamine such as N-methylpropanolamine,N-ethylpropanolamine, N-propylpropanolamine, N-butylpropanolamine,N-octylpropanolamine, N-stearylpropanolamine, N-oleylpropanolamine,N-cyclohexylpropanolamine, N-phenylpropanolamine, andN-benzylpropanolamine; diethanolamine, and dipropanolamine.

Examples of tertiary alkanolamine include monoethanolamine such asN-dimethylethanolamine, N-diethylethanolamine, N-dipropylethanolamine,N-dibutylethanolamine, N-dioctylethanolamine, N-distearylethanolamine,N-dioleylethanolamine, N-dicyclohexylethanolamine,N-diphenylethanolamine, and N-dibenzylethanolamine; monopropanolaminesuch as N-dimethylpropanolamine, N-diethylpropanolamine,N-dipropylpropanolamine, N-dibutylpropanolamine, N-dioctylpropanolamine,N-distearylpropanolamine, N-dioleylpropanolamine,N-dicyclohexylpropanolamine, N-diphenylpropanolamine, andN-dibenzylpropanolamine; diethanolamine such as N-methyldiethanolamine,N-ethyldiethanolamine, N-propyldiethanolamine, N-butyldiethanolamine,N-octyldiethanolamine, N-stearyldiethanolamine, N-oleyldiethanolamine,N-cyclohexyldiethanolamine, N-phenyldiethanolamine, andN-benzyldiethanolamine; dipropanolamine such as N-methyldipropanolamine,N-ethyldipropanolamine, N-propyldipropanolamine, N-butyldipropanolamine,N-octyldipropanolamine, N-stearyldipropanolamine,N-oleyldipropanolamine, N-cyclohexyldipropanolamine,N-phenyldipropanolamine, and N-benzyldipropanolamine; triethanolamine,and tripropanolamine (such as triisopropanolamine).

Among these, from the viewpoint of providing a water-solublemetalworking oil capable of becoming a metalworking fluid having a goodemulsion state and more increased antibacterial properties, antirustproperties, workability, and the like, when combined with dilutionwater, component (C) used in one embodiment of the present inventionpreferably contains at least tertiary alkanolamine, more preferablycontains tertiary alkanolamine and at least one of primary alkanolamineand secondary alkanolamine, and even more preferably contains at leastsecondary alkanolamine and tertiary alkanolamine.

The content of alkanolamine may be preferably 5% by mass or more, morepreferably 10% by mass or more, more preferably 20% by mass or more,even more preferably 30% by mass or more, yet more preferably 35% bymass or more, particularly preferably 40% by mass or more, moreover, 45%by mass or more, 50% by mass or more, or 55% by mass or more, and may be100% by mass or less, 95% by mass or less, 90% by mass or less, 85% bymass or less, 80% by mass or less, 75% by mass or less, 70% by mass orless, or 65% by mass or less based on the total amount (100% by mass) ofcomponent (C) contained in the water-soluble metalworking oil.

Component (C) used in one embodiment of the present invention preferablycontains alicyclic amine.

Examples of alicyclic amine include primary alicyclic amine wherein R inthe above formula (i) is a cycloalkyl group, secondary alicyclic aminewherein at least one R in the above formula (ii) is a cycloalkyl group;and tertiary alicyclic amine wherein at least one R in the above formula(iii) is a cycloalkyl group.

Examples of primary alicyclic amine include N-cyclohexylamine.

Examples of secondary alicyclic amine include monocyclohexylamine suchas N-methylcyclohexylamine, N-ethylcyclohexylamine,N-propylcyclohexylamine, and N-oleylcyclohexylamine;monocyclohexylalkanolamine such as N-cyclohexylethanolamine andN-cyclohexylpropanolamine; and N-dicyclohexylamine.

Examples of tertiary alicyclic amine include dialkylmonocyclohexylaminesuch as N-dimethylcyclohexylamine, N-diethylcyclohexylamine,N-dipropylcyclohexylamine, N-dioleylcyclohexylamine, andN-dicyclohexylamine; monocyclohexyldialkanolamine such asN-cyclohexyldiethanolamine and N-cyclohexyldipropanolamine;monoalkyldicyclohexylamine such as N-methyldicyclohexylamine,N-ethyldicyclohexylamine, N-propyldicyclohexylamine, andN-oleyldicyclohexylamine; dicyclohexylalkanolamine such asN-dicyclohexylethanolamine and N-dicyclohexylpropanolamine; andtricyclohexylamine.

When providing an emulsion-type oil classified as A1 as stipulated inJIS K 2241:2017, component (C) preferably contains one or more selectedfrom dialkylmonocyclohexylamine and monoalkyldicyclohexylamine, and morepreferably contains monoalkyldicyclohexylamine.

When providing a soluble-type oil classified as A2 as stipulated in JISK 2241:2017, component (C) preferably contains one or more selected frommonocyclohexyldialkanolamine and dicyclohexyldialkanolamine, and morepreferably contains monocyclohexyldialkanolamine.

The content of alicyclic amine may be preferably 10% by mass or more,more preferably 20% by mass or more, even more preferably 25% by mass ormore, yet more preferably 30% by mass or more, particularly preferably35% by mass or more, moreover, 37% by mass or more, or 40% by mass ormore, and may be 100% by mass or less, 95% by mass or less, 90% by massor less, 85% by mass or less, 80% by mass or less, 75% by mass or less,70% by mass or less, 65% by mass or less, 60% by mass or less, 55% bymass or less, or 50% by mass or less based on the total amount (100% bymass) of component (C) contained in the water-soluble metalworking oil.

The water-soluble metalworking oil of one embodiment of the presentinvention may contain another amine (including diamine and polyamine)other than alkanolamine and alicyclic amine as component (C).

The content of another amine may be 0 to 50% by mass, 0 to 40% by mass,0 to 30% by mass, 0 to 20% by mass, 0 to 10% by mass, 0 to 5.0% by mass,0 to 2.0% by mass, 0 to 1.0% by mass, 0 to 0.10% by mass, 0 to 0.01% bymass, 0 to 0.001% by mass, 0 to 0.0001% by mass, or 0 to 0.00001% bymass based on the total amount (100% by mass) of component (C) containedin the water-soluble metalworking oil.

<Component (D): Fatty Acid>

Preferably, the water-soluble metalworking oil of one embodiment of thepresent invention further contains a fatty acid (D).

Containing component (D), the water-soluble metalworking oil is capableof becoming a metalworking fluid having more increased emulsionstability, antirust properties, workability, and the like.

In the water-soluble metalworking oil of one embodiment of the presentinvention, one component (D) may be used singly, or two or more may beused in combination.

From the same viewpoint as above, in the water-soluble metalworking oilof one embodiment of the present invention, the content of component (D)may be preferably 5 to 70% by mass, more preferably 7 to 60% by mass,even more preferably 10 to 50% by mass, yet more preferably 13 to 45% bymass, particularly preferably 16 to 40% by mass, moreover, 18% by massor more, 20% by mass or more, 22% by mass or more, or 25% by mass ormore, and may be 38% by mass or less, 35% by mass or less, or 32% bymass or less based on the total amount (100% by mass) of thewater-soluble metalworking oil excluding water.

Also, from the same viewpoint as above, in the water-solublemetalworking oil of one embodiment of the present invention, the contentof component (D) may be preferably 2 to 60% by mass, more preferably 3to 50% by mass, even more preferably 5 to 40% by mass, yet morepreferably 7 to 30% by mass, particularly preferably 9 to 25% by mass,moreover, 10% by mass or more, 12% by mass or more, or 14% by mass ormore, and may be 22% by mass or less, 20% by mass or less, or 18% bymass or less based on the total amount (100% by mass) of thewater-soluble metalworking oil.

Moreover, in the water-soluble metalworking oil of one embodiment of thepresent invention, the mass ratio of the content of component (D) to thecontent of component (A1) [(D)/(A1)] may be preferably 0.01 to 30, morepreferably 0.05 to 25, more preferably 0.10 to 20, even more preferably0.20 to 15, yet more preferably 0.25 to 12.0, particularly preferably0.30 to 8.0, moreover, 0.32 or more, 0.35 or more, 0.50 or more, 0.70 ormore, 0.90 or more, 1.00 or more, 1.20 or more, 1.40 or more, or 1.50 ormore, and may be 7.0 or less, 6.0 or less, 5.0 or less, 4.5 or less, 4.0or less, 3.8 or less, 3.6 or less, 3.4 or less, 3.2 or less, 3.0 orless, 2.8 or less, 2.6 or less, or 2.4 or less.

In the water-soluble metalworking fluid of one embodiment of the presentinvention, from the viewpoint of providing a water-soluble metalworkingoil that has a good stock solution stability and is capable of becominga metalworking fluid having more increased workability, the mass ratioof the content of component (C) to the content of component (D)[(C)/(D)] may be preferably 0.01 to 5.0, more preferably 0.05 to 4.0,more preferably 0.1 to 3.0, even more preferably 0.2 to 2.5, yet morepreferably 0.3 to 2.0, particularly preferably 0.5 to 1.5, moreover, 0.6or more, 0.65 or more, 0.7 or more, 0.75 or more, or 0.8 or more, andmay be 1.4 or less, 1.3 or less, 1.2 or less, or 1.15 or less.

Examples of component (D) used in one embodiment of the presentinvention include fatty acid, hydroxy fatty acid, aliphatic dicarboxylicacid, dimer acid of fatty acid, and polymerized fatty acid of hydroxyunsaturated fatty acid.

Examples of the fatty acid include saturated aliphatic monocarboxylicacid such as octanoic acid, 2-ethylhexanoic acid, decanoic acid,neodecanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid,pentadecanoic acid, heptadecanoic acid, nonadecanic acid, myristic acid,palmitic acid, stearic acid, arachidic acid, behenic acid, andisostearic acid, and unsaturated aliphatic monocarboxylic acid such asoctenoic acid, nonenoic acid, decenoic acid, undecenoic acid, oleicacid, elaidic acid, erucic acid, nervonic acid, linoleic acid,γ-linolenic acid, arachidonic acid, α-linolenic acid, stearidonic acid,eicosapentaenoic acid, and docosahexaenoic acid.

A mixture of unsaturated fatty acid may be used, such as tall oil fattyacid, soybean oil fatty acid, palm oil fatty acid, linseed oil fattyacid, rice bran oil fatty acid, and cottonseed oil fatty acid.

The number of carbon atoms in the fatty acid is preferably 8 to 30, morepreferably 10 to 25, and even more preferably 10 to 20.

Examples of the hydroxy fatty acid include hydroxylauric acid,hydroxymyristic acid, hydroxypalmitic acid, hydroxystearic acid,hydroxyarachic acid, hydroxybehenic acid, and hydroxyoctadecenoic acid.

The number of carbon atoms of the hydroxy fatty acid is preferably 8 to30, more preferably 10 to 25, and even more preferably 10 to 20 carbonatoms.

Examples of the aliphatic dicarboxylic acid include saturated aliphaticdicarboxylic acid such as sebacic acid, dodecanedioic acid,dodecylsuccinic acid, laurylsuccinic acid, stearylsuccinic acid, andisostearylsuccinic acid.

The number of carbon atoms of the aliphatic dicarboxylic acid ispreferably 8 to 30, more preferably 10 to 25, and even more preferably10 to 20 carbon atoms.

Examples of the hydroxy unsaturated fatty acid constituting apolymerized fatty acid of the hydroxy unsaturated fatty acid includericinoleic acid (12-hydroxyoctadec-9-enoic acid). A fatty acid mixturecontaining recinoleic acid, such as castor oil, may be used.

Examples of the polymerized fatty acid of the hydroxy unsaturated fattyacid include condensed fatty acid that is a dehydrative polycondensationproduct of hydroxy unsaturated fatty acid (such as castor oilpolymerized fatty acid that is a dehydrative condensation product of afatty acid mixture containing ricinoleic acid as a main component), andcondensed fatty acid obtained by dehydratively condensing an alcoholichydroxyl group of condensed fatty acid that is a dehydrativepolycondensation product of hydroxy unsaturated fatty acid andmonocarboxylic acid.

Component (D) used in one embodiment of the present invention preferablycontains one or more (preferably two or more, and more preferably threeor more) selected from unsaturated aliphatic monocarboxylic acid,saturated aliphatic dicarboxylic acid, and polymerized fatty acid ofhydroxy unsaturated fatty acid, and more preferably contains all of theunsaturated aliphatic monocarboxylic acid, saturated aliphaticdicarboxylic acid, and polymerized fatty acid of hydroxy unsaturatedfatty acid.

From the viewpoint of providing a water-soluble metalworking oil capableof becoming a metalworking fluid having more increased workability, theacid value of component (D) is usually 0 mgKOH/g or more, preferably 10to 100 mgKOH/g, more preferably 20 to 90 mgKOH/g, and even morepreferably 30 to 80 mgKOH/g.

The hydroxyl value of component (D) is preferably 0 to 80 mgKOH/g, morepreferably 0 to 60 mgKOH/g, and even more preferably 0 to 40 mgKOH/g.

From the above viewpoint, the ratio of the acid value to the hydroxylvalue of component (D) [acid value/hydroxyl value] is preferably 1.5 to15, more preferably from 2.0 to 10, and even more preferably from 2.5 to9.5.

The saponification value of component (D) is preferably 180 to 220mgKOH/g, more preferably 190 to 210 mgKOH/g, and even more preferably195 to 205 mgKOH/g.

Herein, the acid value means a value measured in accordance with JIS K2501:2003 (indicator photometric titration method), the hydroxyl valuemeans a value measured in accordance with JIS K 0070:1992, and thesaponification value means a value measured in accordance with JIS K2503:1996.

<Nonionic Surfactant (E)>

Preferably, the water-soluble metalworking oil of one embodiment of thepresent invention further contains a nonionic surfactant (E). Containingthe nonionic surfactant (E), the water-soluble metalworking oil iscapable of becoming a metalworking fluid having more increased emulsionstability and workability.

In the water-soluble metalworking oil of one embodiment of the presentinvention, one nonionic surfactant (E) may be used singly, or two ormore may be used in combination.

From the above viewpoint, in the water-soluble metalworking oil of oneembodiment of the present invention, the content of component (E) ispreferably 0.5 to 35.0% by mass, more preferably 1.0 to 30.0% by mass,even more preferably 1.2 to 25.0% by mass, and yet more preferably 1.5to 20.0% by mass based, and particularly preferably 1.7 to 16.0% by massbased on the total amount (100% by mass) of the water-solublemetalworking oil excluding water.

When providing an emulsion-type oil classified as A1 as stipulated inJIS K 2241:2017, the content of component (E) may be 15.0% by mass orless, 12.0% by mass or less, 10.0% by mass or less, 8.0% by mass orless, 6.0% by mass or less, 5.0% by mass or less, 4.0% by mass or less,or 3.5% by mass or less based on the total amount (100% by mass) of thewater-soluble metalworking oil excluding water, and the lower limit isas described above.

When providing a soluble-type oil classified as A2 as stipulated in JISK 2241:2017, the content of component (E) may be 2.0% by mass or more,3.0% by mass or more, 4.0% by mass or more, 5.0% by mass or more, 6.0%by mass or more, 7.0° by mass or more, 8.0° by mass or more, 9.0% bymass or more, or 10.0% by mass or more based on the total amount (100%by mass) of the water-soluble metalworking oil excluding water, and theupper limit is as described above.

From the above viewpoint, in the water-soluble metalworking oil of oneembodiment of the present invention, the content of component (E) ispreferably 0.1 to 15.0% by mass, more preferably 0.2 to 12.0% by mass,even more preferably 0.3 to 10.0% by mass, yet more preferably 0.5 to8.0% by mass, and particularly preferably 0.7 to 6.0% by mass based onthe total amount (100% by mass) of the water-soluble metalworking oil.

When providing an emulsion-type oil classified as A1 as stipulated inJIS K 2241:2017, the content of component (E) may be 5.0% by mass orless, 4.5% by mass or less, 4.0% by mass or less, 3.5% by mass or less,3.0% by mass or less, or 2.5% by mass or less based on the total amount(100% by mass) of the water-soluble metalworking oil, and the lowerlimit is as described above.

When providing a soluble-type oil classified as A2 as stipulated in JISK 2241:2017, the content of component (E) may be 1.0% by mass or more,1.2% by mass or more, 1.5% by mass or more, 2.0% by mass or more, 2.5%by mass or more, 3.0% by mass or more, 3.5% by mass or more, or 4.0% bymass or more based on the total amount (100° by mass) of thewater-soluble metalworking oil, and the upper limit is as describedabove.

From the viewpoint of providing a water-soluble metalworking oil capableof becoming a metalworking fluid having more increased emulsionstability and workability, the HLB of component (E) used in oneembodiment of the present invention is preferably 6.0 or more, morepreferably 7.0 or more, even more preferably 8.0 or more, yet morepreferably 9.0 or more, and particularly preferably 10.0 or more, and is18.0 or less, preferably 17.0 or less, more preferably 16.0 or less,even more preferably 15.0 or less, and yet more preferably 14.5 or less.

Herein, HLB means a value calculated by Griffin's method.

Examples of component (E) used in one embodiment of the presentinvention include alkylene glycol, polyoxyalkylene alkyl ether,polyoxyalkylene aryl ether, polyoxyalkylenealkylamine (a cocoaminealkylene oxide adduct), an alkylphenol alkylene oxide adduct, a higheralcohol alkylene oxide adduct, a polyoxyalkylene fatty acid ester, afatty acid ester of glycerin and pentaerythritol, a fatty acid ester ofsucrose, a fatty acid ester of a polyoxyalkylene adduct of polyhydricalcohol, alkyl polyglycoside, and fatty acid alkanolamide.

Among these, from the viewpoint of providing a water-solublemetalworking oil capable of becoming a metalworking fluid having moreincreased emulsion stability and workability, component (E) used in oneembodiment of the present invention preferably contains one or moreselected from polyoxyalkylene alkyl ether and polyoxyalkylenealkylamine.

The total content of polyoxyalkylene alkyl ether and polyoxyalkylenealkylamine is preferably 50 to 100% by mass, more preferably 70 to 100%by mass, even more preferably 80 to 100% by mass, yet more preferably 90to 100% by mass, and particularly preferably 95 to 100% by mass based onthe total amount (100% by mass) of component (E) contained in thewater-soluble metalworking oil.

<Sulfuric Extreme Pressure Agent>

Containing oil-soluble PAG (A1) as the base oil (A), the water-solublemetalworking oil of the present invention is capable of being preparedinto a metalworking fluid having excellent workability even withoutcontaining a sulfuric extreme pressure agent that causes corrosion of acopper-containing member. Accordingly, from the viewpoint of providing awater-soluble metalworking oil capable of becoming a metalworking fluidthat is highly effective for suppressing corrosion of acopper-containing member, the water-soluble metalworking oil of oneembodiment of the present invention is preferably substantially free ofa sulfuric extreme pressure agent.

Examples of the sulfuric extreme pressure agent include sulfurizedolefin, sulfurized lard, alkyl polysulfide, and sulfurized fatty acid.

Herein, the expression “substantially free of a sulfuric extremepressure agent” is a provision obviating an embodiment wherein asulfuric extreme pressure agent is contained for a specific purpose, butis not a provision obviating an embodiment wherein a sulfuric extremepressure agent is inadvertently contained as an impurity of othercomponents. However, even in consideration of an embodiment wherein asulfuric extreme pressure agent is inadvertently contained, the contentof a sulfuric extreme pressure agent is preferably as small as possiblefrom the viewpoint of providing a water-soluble metalworking oil capableof becoming a metalworking fluid that is highly effective forsuppressing corrosion of a copper-containing member.

A specific content of a sulfuric extreme pressure agent is preferablyless than 10 parts by mass, more preferably less than 1 part by mass,more preferably less than 0.1 parts by mass, even more preferably lessthan 0.01 parts by mass, and particularly preferably less than 0.001parts by mass based on 100 parts by mass of the total amount ofcomponent (A1) contained in the water-soluble metalworking oil.

<Other Various Additives>

The water-soluble metalworking oil of one embodiment of the presentinvention may further contain, as necessary, other various additivesother than the above components (A) to (E) as long as the effects of thepresent invention are not impaired.

Examples of such other various additives include anionic surfactants,cationic surfactants, petroleum sulfonates, non-sulfuric extremepressure agents, metal deactivators, emulsification aids, antibacterialagents, antifoaming agents, antioxidants, and oily agents.

One of these various additives may be used singly, or two or more may beused in combination.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the content of each of these various additives is suitablyset according to the type and the function of each component, and ispreferably 0.001 to 50% by mass, more preferably 0.01 to 40% by mass,even more preferably 0.07 to 30% by mass, and yet more preferably 0.1 to20% by mass based on the total amount (100% by mass) of thewater-soluble metalworking oil excluding water.

In the water-soluble metalworking oil of one embodiment of the presentinvention, the content of each of these various additives is suitablyset according to the type and the function of each component, and ispreferably 0.001 to 25% by mass, more preferably 0.01 to 20% by mass,even more preferably 0.03 to 15% by mass, and yet more preferably 0.05to 10% by mass based on the total amount (100% by mass) of thewater-soluble metalworking oil.

Examples of the anionic surfactant include polyoxyethylene alkyl ethercarboxylic acids, polyoxyethylene alkyl ether phosphoric acids,alkylbenzene sulfonic acids, α-olefinsulfonic acids, and salts thereof.

The acid value of anionic surfactants is preferably 20 to 250 mgKOH/g,more preferably 30 to 200 mgKOH/g, even more preferably 40 to 190mgKOH/g, and yet more preferably 50 to 180 mgKOH/g.

Examples of cationic surfactants include alkyltrimethylammonium salts,dialkyldimethylammonium salts, and alkyldimethylbenzylammonium salts.

Examples of petroleum sulfonates include calcium sulfonate, sodiumsulfonate, and magnesium sulfonate.

Examples of non-sulfuric extreme pressure agents include chloric extremepressure agents such as chlorinated paraffin, chlorinated fatty acids,and chlorinated fatty oils; and phosphoric extreme pressure agents suchas phosphoric esters, phosphorous esters, thiophosphoric esters, saltsthereof, phosphines, and tricresyl phosphate.

Examples of metal deactivators include benzotriazoles, imidazolines,pyrimidine derivatives, and thiadiazoles.

Examples of emulsifying aids include unsaturated fatty acid esters suchas methyl oleate, ethyl oleate, and propyl oleate; and aromatic alcoholssuch as 2-phenoxyethanol and 2-phenylethyl alcohol.

Examples of antibacterial agents include isothiazoline compounds,triazine compounds, alkylbenzimidazole compounds, and metal pyrithionesalts.

Examples of antifoaming agents include silicone antifoaming agents,fluorosilicone antifoaming agents, and polyacrylates.

Examples of antioxidants include amine antioxidants such as alkylateddiphenylamine, phenylnaphthylamine, and alkylated phenylnaphthylamine;and phenolic antioxidants such as 2,6-di-t-butylphenol,4,4′-methylenebis(2,6-di-t-butylphenol),isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, andn-octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate.

Examples of oily agents include alcohols such as lauryl alcohol,myristyl alcohol, palmityl alcohol, stearyl alcohol, and oleyl alcohol.

<Method for Producing Water-Soluble Metalworking Oil>

The method for producing a water-soluble metalworking oil of oneembodiment of the present invention is not particularly limited, and ispreferably a method comprising the step of blending the above component(A) and, optionally, the components (B) to (E) and various otheradditives. The order of blending the respective components can besuitably set.

[Properties of Water-Soluble Metalworking Oil]

The acid value of the water-soluble metalworking oil of one embodimentof the present invention is preferably 10 to 70 mgKOH/g, more preferably15 to 60 mgKOH/g, even more preferably 20 to 50 mgKOH/g, and yet morepreferably 25 to 40 mgKOH/g.

The base value of the water-soluble metalworking oil of one embodimentof the present invention is preferably 10 to 100 mgKOH/g, morepreferably 20 to 90 mgKOH/g, even more preferably 30 to 80 mgKOH/g, andyet more preferably 40 to 70 mgKOH/g.

Herein, the base value means a value measured in accordance with JIS K2501:2003 (HCl method).

The ratio of the base value to the acid value [base value/acid value] ofthe water-soluble metalworking oil of one embodiment of the presentinvention is preferably 1.0 to 4.0, more preferably 1.1 to 3.5, evenmore preferably 1.3 to 3.2, yet more preferably 1.5 to 3.0, andparticularly preferably 1.7 to 2.8.

When the ratio is 1.0 or more, a water-soluble metalworking oil havinggood decay resistance can be provided. On the other hand, when the ratiois 4.0 or less, irritation to the human skin can be small, and thus thewater-soluble metalworking oil is preferable in terms of handleability.

[Form of Metalworking Fluid]

The metalworking fluid of the present invention is obtained by using theabove metalworking oil of one embodiment of the present invention as astock solution, and adding dilution water to the metalworking oil.

Dilution water may be any of, for example, distilled water, ionexchanged water, tap water, or water for industrial use.

The amount of dilution water added when preparing the metalworking fluidis more than 400 parts by mass based on 100 parts by mass of the totalamount of components other than water of the water-soluble metalworkingoil and, preferably, is suitably regulated so as to attain a desireddilute concentration.

The dilute concentration of the metalworking fluid of one embodiment ofthe present invention is preferably 1 to 50% by volume, more preferably3 to 40% by volume, and even more preferably 5 to 20% by volume.

Herein, the “dilute concentration of the metalworking fluid” means avalue calculated from the following equation:

“Dilute concentration of metalworking fluid (% by volume)”=[Volume ofmetalworking oil before dilution]/[[Volume of metalworking oil beforedilution]+[Volume of dilution water]]×100.

[Applications of Metalworking Fluid, and Metalworking Method]

The metalworking fluid of one suitable embodiment of the presentinvention has better workability than conventional metalworking fluids,and can be suitably used in metalworking. The metalworking fluid of onesuitable embodiment of the present invention can exhibit excellentworkability even without containing a sulfuric extreme pressure agent.Accordingly, corrosion of copper-containing members constituting aprocessing machine caused by a sulfuric extreme pressure agent can beeffectively suppressed.

The workpiece to be processed using the metalworking fluid of oneembodiment of the present invention is not particularly limited, and themetalworking fluid is particularly suitable for workpieces composed ofmetals selected from the group consisting of iron, titanium, aluminum,titanium alloy, alloy steel, nickel-based alloy, niobium alloy, tantalumalloy, molybdenum alloy, tungsten alloy, stainless steel, aluminumalloy, and high-manganese steel. Among these, the metalworking fluid isparticularly suitable for a workpiece having a member containing atleast iron or aluminum.

Accordingly, the present invention can also provide [1] and [2] below:

[1] A method of use comprising applying the above metalworking fluid ofone embodiment of the present invention to processing of a metalworkpiece.[2] A metalworking method comprising applying the above metalworkingfluid of one embodiment of the present invention to process a metalworkpiece.

The workpiece set forth in [1] and [2] is as described above, and issuitably a workpiece having a member containing at least iron oraluminum.

Moreover, according to the methods set forth in [1] and [2], corrosionof copper-containing members constituting a processing machine used toprocess the workpiece can be suppressed.

In [1] and [2], examples of processing of the workpiece include cutting,grinding, punching, polishing, spinning, drawing, and rolling.

In the method of use according to [1] and the metalworking methodaccording to [2], the metalworking fluid is used such that the abovewater-soluble metalworking oil of one embodiment of the presentinvention is blended with dilution water and then fed to, and thusbrought into contact with, the workpiece. The metalworking fluidprovides lubrication between the workpiece and the work tool. Moreover,the metalworking fluid is also used to remove swarf, prevent rust of theworkpiece, cool the tool and the work piece, and the like.

EXAMPLES

Next, the present invention will now be described in more detail by wayof Examples, but the present invention is not limited to these Examplesin any way.

In the following Examples, the methods for measuring and calculating thefollowing physical property values are as follows:

(1) Kinematic Viscosity, Viscosity Index

Measured and calculated in accordance with JIS K 2283:2000.

(2) HLB

Calculated based on Griffin's method.

(3) Acid Value (Indicator Photometric Titration Method)

Measured in accordance with JIS K 2501:2003 (indicator photometrictitration method).

(4) Base Value (HCl Method)

Measured in accordance with JIS K 2501:2003 (HCl method).

Examples 1 to 8, Comparative Examples 1 to 4

Various components of the types shown in Tables 2 and 3 were added andmixed in the amounts shown in Tables 2 and 3 to prepare respectivewater-soluble metalworking oils. Details of each component used in thepreparation of the water-soluble metalworking oils are as follows.

<Component (A1)>

-   -   Oil-soluble PAG (a-1): Oil-soluble polyalkylene glycol        corresponding to viscosity grade VG32 stipulated in ISO 3448.    -   Oil-soluble PAG (a-2): Oil-soluble polyalkylene glycol        corresponding to viscosity grade VG46 stipulated in ISO 3448.    -   Oil-soluble PAG (a-3): Oil-soluble polyalkylene glycol        corresponding to viscosity grade VG68 stipulated in ISO 3448.

<Component (A2)>

-   -   Paraffinic mineral oil: Paraffinic mineral oil having kinematic        viscosity at 40° C.=7.117 mm²/s, viscosity index=109.

<Component (B)>

-   -   Water: Ion exchanged water

<Component (C)>

-   -   Amine (c-1): N-Methylethanolamine, secondary monoamine    -   Amine (c-2): N-Cyclohexyldiethanolamine, tertiary monoamine    -   Amine (c-3): N-Methyldiethanolamine, tertiary monoamine    -   Amine (c-4): Triisopropanolamine, tertiary monoamine    -   Amine (c-5): N-Methyldicyclohexylamine, tertiary monoamine

<Component (D)>

-   -   Fatty acid (d-1): Neodecanoic acid    -   Fatty acid (d-2): Tall oil fatty acid    -   Fatty acid (d-3): Dodecanedioic acid    -   Fatty acid (d-4): Castor oil polymerized fatty acid (ricinoleic        acid hexamer, acid value: 31.6 mgKOH/g, hydroxyl value: 9.4        mgKOH/g, acid value/hydroxyl value=3.36)

<Component (E)>

-   -   Nonionic surfactant (e-1): Cocoamine ethylene oxide 2-mol        adduct, HLB=6.3    -   Nonionic surfactant (e-2): Polyoxyalkylene alkyl ether, HLB=12.7

<Sulfuric Extreme Pressure Agent>

-   -   Dioctylpolysulfide

<Other Components>

-   -   Anionic surfactant: Polyoxyethylene oleyl ether carboxylic acid,        acid value=69.3 mgKOH/g.    -   Metal deactivator: Benzotriazole    -   Emulsifying aid: 2-Phenoxyethanol    -   Antibacterial agent: 1,2-Benzoisothiazolin-3-on    -   Antifoaming agent: Silicone defoaming agent

The acid value, the base value, and the ratio of base value/acid valueof the prepared water-soluble metalworking oils were measured andcalculated and, also, the following evaluations were made using thewater-soluble metalworking oils. The results thereof are shown in Tables2 and 3.

(1) Classification of Oil Type

In accordance with the provisions of JIS K 2241:2017, the water-solublemetalworking oils were classified as emulsion-type oils A1 orsoluble-type oils A2 of this standard. In Tables 2 and 3, “E” is givenwhen classified as an emulsion-type oil A1, and “S” is given whenclassified as a soluble-type oil A2.

(2) Copper Plate Corrosion Test

A test was conducted under 50° C. oil temperature and 48-hour conditionsby a test method in accordance with JIS K 2513, then the degree ofdiscoloration of a copper plate was visually inspected, and the degreeof corrosion of the copper plate was evaluated based on “Table 1Classification of Corrosion by Copper Plate Corrosion Standard” of JIS K2513 shown in Table 1 below. Tables 2 and 3 provide “discolorationnumbers (subclassification symbols)”, and the discoloration numbersindicate the degree of corrosion of a copper plate by way of numericalvalues of 1 to 4, with a greater numerical value indicating severercorrosion.

TABLE 1 Discoloration Degree of number discoloration State ofdiscoloration Copper plate — For a copper plate corrosion immediatelystandard, the state of a copper after being plate surface immediatelypolished after being polished is indicated, but such a state is unlikelyobtained after testing even from a sample with completely no corrosion.1 Slightly (a) Pale orange (almost the same discolored color as copperplate immediately after being polished) (b) Dark orange 2 Mildly (a)Pink discolored (b) Pale pink with purple hue (c) Multi-colored patternwith dark pink, blue with purple hue, etc. over orange (d) Silver withpale gold hue (e) Brass or gold 3 Severely (a) Reddish brown patternover brass discolored (b) Multi-colored pattern with red and green(peacock pattern) 4 Corroded (a) Greenish blue purple or black to suchan extent that the underlayer is visible (b) Graphite-like black ormatte black (c) Glossy black

(3) Evaluation of Workability

A water-soluble metalworking oil was diluted with ion exchanged water toprepare a metalworking fluid having a dilute concentration of 5° byvolume. Using the prepared metalworking fluid, a pilot hole was drilledunder the following conditions, and then a tapping torque test wasperformed to measure the maximum tapping torque during processing.Measurement was performed three times, and the average value and themaximum value of the results are shown in Tables 2 and 3.

It can be said that the smaller the average value and the maximum valueare, the better the metal workability of the metalworking fluid used is.

<Pilot Hole Drilling Conditions>

-   -   Machine used: Tapping Center MTV-T350 (manufactured by Mectron        Inc.)    -   Drill: SG-ESS (manufactured by Nachi-Fujikoshi Corporation),        drill diameter: 5.56 mm        -   Cutting speed: 31 m/min        -   Rotational speed: 1798 min-1        -   Feeding speed: 260 ram/min        -   Feed per revolution: 0.145 mm/rev        -   Depth: 15 mm

<Tapping Torque Test>

-   -   Tester used: Megatap II (micro-electronische Gerate GmbH)    -   Tap: Nu-Roll Tap VP-NRT B M6×1 (manufactured by OSG Corporation)        -   Cutting speed: 10 m/min        -   Feed: 1.0 mm/rev        -   Depth: 12 mm        -   Number of processed samples n: 3        -   Material to be cut: SCM440 (JIS standard) (chrome molybdenum            steel)

TABLE 2 Com- Com- parative parative Ex- Ex- Ex- Ex- Ex- Ex- Ex- Ex-ample ample ample ample ample ample ample ample 1 2 3 4 5 6 1 2 Com-Component (A1) Oil-soluble PAG (a-1) % by mass 1.00 3.00 5.00 7.00position Oil-soluble PAG (a-2) % by mass 5.00 of Oil-soluble PAG (a-3) %by mass 5.00 water- Component (A2) Paraffinic mineral oil % by mass 5.00soluble Component (B) Water % by mass 62.25 60.25 58.25 56.25 58.2558.25 58.25 58.25 metal- Component (C) Amine (c-1) % by mass 3.50 3.503.50 3.50 3.50 3.50 3.50 3.50 working Amine (c-2) % by mass 6.00 6.006.00 6.00 6.00 6.00 6.00 6.00 oil Amine (c-3) % by mass 3.50 3.50 3.503.50 3.50 3.50 3.50 3.50 Amine (c-4) % by mass Amine (c-5) % by massComponent (D) Fatty acid (d-1) % by mass 2.00 2.00 2.00 2.00 2.00 2.002.00 2.00 Fatty acid (d-2) % by mass 2.00 2.00 2.00 2.00 2.00 2.00 2.002.00 Fatty acid (d-3) % by mass 1.50 1.50 1.50 1.50 1.50 1.50 1.50 1.50Fatty acid (d-4) % by mass 6.00 6.00 6.00 6.00 6.00 6.00 6.00 6.00Component (E) Nonionic surfactant (e-1) % by mass 4.00 4.00 4.00 4.004.00 4.00 4.00 4.00 Nonionic surfactant (e-2) % by mass 1.00 1.00 1.001.00 1.00 1.00 1.00 1.00 Sulfuric extreme Dioctylpolysulfide % by mass5.00 pressure agent Other Anionic surfactant % by mass 2.00 2.00 2.002.00 2.00 2.00 2.00 2.00 components Metal deactivator % by mass 1.001.00 1.00 1.00 1.00 1.00 1.00 1.00 Emulsifying aid % by mass 4.00 4.004.00 4.00 4.00 4.00 4.00 4.00 Antibacterial agent % by mass 0.20 0.200.20 0.20 0.20 0.20 0.20 0.20 Antifoaming agent % by mass 0.05 0.05 0.050.05 0.05 0.05 0.05 0.05 Total % by mass 100.00 100.00 100.00 100.00100.00 100.00 100.00 100.00 Content of each Component (A1) + (A2) % bymass 2.6 7.5 12.0 16.0 12.0 12.0 0 0 component Component (B) % by mass165 152 140 129 140 140 140 140 based on total Component (C) % by mass34.4 32.7 31.1 29.7 31.1 31.1 31.1 31.1 amount (100% Component (D) % bymass 30.5 28.9 27.5 26.3 27.5 27.5 27.5 27.5 by mass) of oil Component(E) % by mass 13.2 12.6 12.0 11.4 12.0 12.0 12.0 12.0 excluding waterSulfuric extreme % by mass 0 0 0 0 0 0 0 12.0 pressure agentWater-soluble % by mass 0 0 0 0 0 0 0 0 PAG + MPEG Component(C)/Component (A1) — 13.00 4.33 2.60 1.86 2.60 2.60 — — Component(D)/Component (A1) — 11.50 3.83 2.30 1.64 2.30 2.30 — — Component(C)/Component (D) — 1.13 1.13 1.13 1.13 1.13 1.13 1.13 1.13 PropertiesAcid value of water-soluble mgKOH/g 26.11 26.11 26.11 26.11 26.11 26.1126.11 26.12 metalworking oil Base value of water-soluble mgKOH/g 67.1667.16 67.16 67.16 67.16 67.16 67.16 67.16 metalworking oil Basevalue/acid value — 2.57 2.57 2.57 2.57 2.57 2.57 2.57 2.57 Evaluation(1) Classification of oil type — S S S S S S S S item (2) Copper platecorrosion test JIS K2513 — 1(b) 1(1b) 1(1b) 1(1b) 1(1b) 1(1b) 1(1b)4(4c) (3) Evaluation Average value N · cm 249 233 230 229 225 222 291235 of workability of tap torque Maximum value N · cm 360 340 340 340335 335 425 345 of tap torque

TABLE 3 Com- Com- parative parative Ex- Ex- Ex- Ex- ample ample ampleample 7 8 3 4 Composition Component (A1) Oil-soluble PAG (a-1) % by mass51.65 20.00 of Oil-soluble PAG (a-2) % by mass water-soluble Oil-solublePAG (a-3) % by mass metalworking Component (A2) Paraffinic mineral oil %by mass 31.65 51.65 31.65 oil Component (B) Water % by mass 8.00 8.008.00 8.00 Component (C) Amine (c-1) % by mass 1.00 1.00 1.00 1.00 Amine(c-2) % by mass Amine (c-3) % by mass 3.50 3.50 3.50 3.50 Amine (c-4) %by mass 4.50 4.50 4.50 4.50 Amine (c-5) % by mass 6.50 6.50 6.50 6.50Component (D) Fatty acid (d-1) % by mass 1.85 1.85 1.85 1.85 Fatty acid(d-2) % by mass 5.00 5.00 5.00 5.00 Fatty acid (d-3) % by mass 1.00 1.001.00 1.00 Fatty acid (d-4) % by mass 11.00 11.00 11.00 11.00 Component(E) Nonionic surfactant (e-1) % by mass Nonionic surfactant (e-2) % bymass 1.90 1.90 1.90 1.90 Sulfuric extreme Dioctylpolysulfide % by mass20.00 pressure agent Other Anionic surfactant % by mass components Metaldeactivator % by mass 0.80 0.80 0.80 0.80 Emulsifying aid % by mass 3.003.00 3.00 3.00 Antibacterial agent % by mass 0.20 0.20 0.20 0.20Antifoaming agent % by mass 0.10 0.10 0.10 0.10 Total % by mass 100.00100.00 100.00 100.00 Content of each Component (A1) + (A2) % by mass56.1 21.7 0 0 component Component (B) % by mass 8.7 8.7 8.7 8.7 based ontotal Component (C) % by mass 16.8 16.8 16.8 16.8 amount (100% Component(D) % by mass 20.5 20.5 20.5 20.5 by mass) of oil Component (E) % bymass 2.1 2.1 2.1 2.1 excluding water Sulfuric extreme pressure agent %by mass 0 0 0 21.7 Water-soluble PAG + MPEG % by mass 0 0 0 0 Component(C)/Component (A1) — 0.30 0.78 — — Component (D)/Component (A1) — 0.360.94 — — Component (C)/Component (D) — 0.82 0.82 0.82 0.82 PropertiesAcid value of water-soluble metalworking oil mgKOH/g 28.20 28.20 28.2028.26 Base value of water-soluble metalworking oil mgKOH/g 52.52 52.5252.52 52.52 Base value/acid value — 1.86 1.86 1.86 1.86 Evaluation (1)Classification of oil type — E E E E item (2) Copper plate corrosiontest JIS K2513 — 1(1b) 1(1b) 1(1b) 4(4c) (3) Evaluation of Average valueof tap torque N · cm 224 245 292 231 workability Maximum value of taptorque N · cm 340 360 430 350

From Tables 2 and 3, the metalworking fluids prepared by diluting thewater-soluble metalworking oils of Examples 1 to 8, irrespective ofbeing a soluble type or an emulsion type, suppressed corrosion of acopper plate and also had good workability. On the other hand, themetalworking fluids prepared by diluting the water-soluble metalworkingoils of Comparative Examples 1 to 4 were inferior with respect to atleast one of the copper plate corrosion suppressing effect andworkability.

1. A water-soluble metalworking oil comprising a base oil (A) comprisingoil-soluble polyalkylene glycol (A1), wherein a total content ofwater-soluble polyalkylene glycol and methoxypolyethylene glycol is lessthan 60% by mass based on the total amount excluding water.
 2. Thewater-soluble metalworking oil according to claim 1, wherein the totalcontent of water-soluble polyalkylene glycol and methoxypolyethyleneglycol is less than 10 parts by mass based on 100 parts by mass of thetotal amount of component (A1).
 3. The water-soluble metalworking oilaccording to claim 1, which is substantially free of a sulfuric extremepressure agent.
 4. The water-soluble metalworking oil according to claim1, further comprising water (B).
 5. The water-soluble metalworking oilaccording to claim 1, wherein the content of component (A1) in component(A) is 10 to 100% by mass based on the total amount of component (A)contained in the water-soluble metalworking oil.
 6. The water-solublemetalworking oil according to claim 1, wherein the content of component(A1) is 0.01% by mass or more based on the total amount of thewater-soluble metalworking oil excluding water.
 7. The water-solublemetalworking oil according to claim 1, further comprising an aminecompound (C).
 8. The water-soluble metalworking oil according to claim1, further comprising a fatty acid (D).
 9. The water-solublemetalworking oil according to claim 1, further comprising a nonionicsurfactant (E).
 10. The water-soluble metalworking oil according toclaim 1, which is an emulsion-type oil classified as A1 as stipulated inJIS K 2241:2017.
 11. The water-soluble metalworking oil according toclaim 1, which is a soluble-type oil classified as A2 as stipulated inJIS K 2241:2017.
 12. A water-soluble metalworking oil comprising a baseoil (A) comprising oil-soluble polyalkylene glycol (A1), wherein a totalcontent of water-soluble polyalkylene glycol and methoxypolyethyleneglycol is less than 10 parts by mass based on 100 parts by mass of thetotal amount of component (A).
 13. A metalworking fluid obtained byblending the water-soluble metalworking oil of claim 1 with dilutionwater.
 14. A metalworking method comprising processing a workpiececomprising metal by application of the metalworking fluid according toclaim
 13. 15. The metalworking method according to claim 14, wherein theworkpiece has a member comprising at least iron or aluminum.
 16. Themetalworking method according to claim 14, wherein corrosion of acopper-containing member constituting a processing machine used inprocessing of the workpiece is suppressed.